Hypodermic needle with protective sheath

ABSTRACT

A hypodermic needle has a retractable tubular sheath slidably mounted on its forward end and movable relative thereto between a rearward retracted position exposing the front end of the needle and a forward protective position enclosing the front end of the needle. In one embodiment, a spring within the sheath urges the sheath to the forward protective position enclosing the front end of the needle. The rear of the sheath cooperates with pins on the needle to engage them upon relative rotation in one direction to allow rotation as a single unit to connect the needle to fluid ejection or withdrawal members. Relative rotation in the opposite direction disengages the pins allowing the sheath to be moved rearward causing the front end of the needle to protrude beyond the front end of the sheath and to lock the needle and sheath together upon further relative rotation in the opposite direction to disconnect and dispose of the needle without inadvertent injury by contact with the needle. Another embodiment has protrusions on the needle and a retractable sheath slidably mounted on the needle and movable between a rearward retracted position exposing the needle front end and a forward protective position engaging the protrusions and covering the front end of the needle. A further modification has a tubular catheter slidably received on the needle for hypodermic penetration therewith which is removably connected to the sheath whereby when the sheath and needle are removed from the catheter only the catheter remains in place.

CROSS REFERENCE TO RELATED CASE

This application is a division of copending application Ser. No.462,788, filed Jan. 10, 1990,, now U.S. Pat. No. 5,049,136.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to hypodermic needles which are adaptedto inject substances into humans and animals and/or to withdrawspecimens therefrom, and more particularly to a hypodermic needle havinga protective sheath for shielding the needle during use, storage, anddisposal.

2. Brief Description of the Prior Art

The shielding of hypodermic needles is of critical concern to healthpractitioners from the standpoint of both handling the needle and thedisposal of used needles. Accidental exposure or puncture by the sharpend of the needle can have very serious and even fatal healthconsequences. For example, the needle may be contaminated with diseasessuch as hepatitis or A.I.D.S. It is therefore desirable that the needlebe shielded immediately after use with a minimum of handling and bedisposed of in a reliable and efficient manner to provide protectionfrom accidental puncture.

There are several patents which disclose apparatus for shielding ahypodermic needle against accidental puncture and for covering theneedle for disposal. Most of these patents teach devices which aremounted on the dispensing syringe, and the shielding member remains in aposition covering the needle after use.

A major disadvantage with these shielding devices is that the entiredispensing syringe must also be discarded along with the needle.Disposal of hazardous waste in health facilities is a precise science.Special containers are used and rigid guidelines are followed indisposal operations. Often the practitioner is charged by the weight ofthe hazardous materials which are to be disposed of. The cost of specialhandling of hazardous material is passed along to the patient. It wouldbe desirable to provide a device which would allow the needle to beseparated from the syringe whereby both members may be disposed ofseparately.

U.S. Pat. Nos. 3,370,588, 3,405,713, and 4,747,835 are examples ofremovable needle shielding devices which are manually removed andreplaced by pulling them completely off of the syringe or needle base.These devices have the disadvantage of losing the shield when removedand leaving the needle exposed and also present a risk to the persondoing the handling when replacing the shield.

Sampson et al, U.S. Pat. No. 4,425,120 discloses a shielded hypodermicsyringe having a tubular sleeve which slides on the barrel of thesyringe and is movable from a forward shielding position to a rearwardnon-shielding position and utilizes slots in the sleeve to lock it neither position. This device requires manually moving the shield to theshielding position and consequently there is substantial risk to theperson doing the handling and the possibility of the shield beingaccidentally left in the non-shielding position.

U.S. Pat. Nos. 4,655,751, 4,702,738, and 4,702,739 are examples of othershield devices which are mounted on the syringe rather than on theneedle and which require manual movement of the shield to the extendedposition. These patents also inherently present a risk to the persondoing the handling and the possibility of the shield being accidentallyleft in the nonshielding position.

Laico et al, U.S. Pat. No. 4,804,372 teaches a protective sheath whichis mounted on the hypodermic needle base. The shield device comprises apair of telescopic tubular shields slidably mounted to the needle base.Detent locking members lock the shields in a non-retractable extendedposition. This device also requires manually moving the shields to theshielding position with the resultant risk to the person doing thehandling and the possibility of the shield being accidentally left inthe non-shielding position.

U.S. Pat. Nos. 3,073,306, and 4,816,022 are also examples of othershield devices which are mounted on the needle rather than the syringebut still require manual movement of the shield to the extendedposition. These devices also inherently present a risk to the persondoing the handling and the possibility of the shield being accidentallyleft in the non-shielding position.

White, U.S. Pat. No. 2,876,770 discloses a shielded hypodermic syringewhich hides the needle from view and also shields the needle after use.The shield device comprises a pair of telescopic tubular shields urgedapart by a compression spring. One end of the inner member is mounted onthe syringe and its other end is provided with a stop flange. The outermember is slidably received on the inner member and has a ring-likeretainer mounted at its rearward end having an inwardly facing flangewhich engages the inner member flange in the normally extended position.The retainer ring exterior has a semicircular step portion which extendsrearward. When the outer member is rotated to one position, the stepportion will engage the stop pin, and when rotated to another positionstep portion will engage end of the syringe whereby selective exposureof the end of the needle is controlled. This device does not provide forpositive locking of the outer member in a non-retractable extendedposition with the resultant risk of accidental retraction of the shieldduring handling or disposal.

Hall, U.S. Pat. No. 4,416,663 discloses a shielded, self sterilizing,hypodermic syringe comprising a pair of telescopic tubular membershaving a compression spring disposed therebetween. The outer member issnap fitted onto the needle and the inner member is slidably mountedwithin the outer member to extend outwardly beyond the forward end. Theinner member is an enclosed capsule containing sterilizing material andhas perforated ends. When the capsule is pressed against the skin theneedle will penetrate and pass through the sterilizing material to exitthe outer end on its forward motion and when the needle is withdrawn thespring will position the capsule such that the needle tip is disposedwithin the sterilizing material. This device also does not provide forpositive locking of the outer member in a non-retractable extendedposition with the resultant risk of accidental retraction of the shieldduring handling.

The present invention is distinguished over the prior art in general,and these patents in particular by a sheathed hypodermic needle having aretractable tubular sheath slidably mounted on its forward end andmovable relative thereto between a rearward retracted position exposingthe front end of the needle and a forward protective position enclosingthe front end of the needle. In one embodiment, a spring within thesheath urges the sheath to the forward protective position enclosing thefront end of the needle. The rear of the sheath cooperates with pins onthe needle to engage the pins upon relative rotation in one direction toallow rotation as a single unit to connect the needle to fluid ejectionor withdrawal members. Relative rotation in the opposite directiondisengages the pins to allow the sheath to be moved rearward causing thefront end of the needle to protrude beyond the front end of the sheathand to lock the needle and sheath together upon further relativerotation in the same said opposite direction to disconnect and disposeof the needle without inadvertent injury by contact with the needle.Another embodiment has protrusions on the needle and a retractablesheath slidably mounted on the needle and movable between a rearwardretracted position exposing the needle front end and a forwardprotective position engaging the protrusions and covering the front endof the needle. A further modification has a tubular catheter slidablyreceived on the needle for hypodermic penetration therewith which isremovably connected to the sheath whereby when the sheath and needle areremoved from the catheter only the catheter remains in place.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a sheathedhypodermic needle having a protective sheath which will automaticallyassume an extended protective position covering the outer end of theneedle.

It is another object of this invention to provide a sheathed hypodermicneedle having a protective sheath which facilitates the safe, quick, andeasy installation of the needle onto and off of the end of a syringe orintravenous tube.

Another object of this invention to provide a sheathed hypodermic needlehaving a protective sheath which will automatically assume a lockedextended protective position covering the outer end of the needle whenit is removed from the end of a syringe or intravenous tube and may besafely disposed of separately from the syringe or other disposablematerials.

Another object of this invention is to provide a sheathed hypodermicneedle having a retractable sheath which is normally yieldingly held inan extended protective position covering the outer end of the needle.

Another object of this invention is to provide a sheathed hypodermicneedle having a retractable sheath which is easily and quickly locked inan extended protective position covering the outer end of the needle toprevent accidental retraction and exposure of the end of the needle.

Another object of this invention is to provide a sheathed hypodermicneedle having a retractable sheath which will prevent the needle frombeing reused once it has been locked into the extended position.

A further object of this invention is to provide a sheathed hypodermicneedle having a retractable sheath which does not require modificationsto the syringe or other instruments to which it is attached.

A still further object of this invention is to provide a sheathedhypodermic needle having a retractable sheath which is simple in designand construction, economical to manufacture and rugged and reliable inuse.

Other objects of the invention will become apparent from time to timethroughout the specification and claims as hereinafter related.

The above noted objects and other objects of the invention areaccomplished by a sheathed hypodermic needle having a retractabletubular sheath slidably mounted thereon. A hypodermic needle has aretractable tubular sheath slidably mounted on its forward end andmovable relative thereto between a rearward retracted position exposingthe front end of the needle and a forward protective position enclosingthe front end of the needle. In one embodiment, a spring within thesheath urges the sheath to the forward protective position enclosing thefront end of the needle. The rear of the sheath cooperates with pins onthe needle to engage the pins upon relative rotation in one direction toallow rotation as a single unit to connect the needle to fluid ejectionor withdrawal members. Relative rotation in the opposite directiondisengages the pins to allow the sheath to be moved rearward causing thefront end of the needle to protrude beyond the front end of the sheathand to lock the needle and sheath together upon further relativerotation in the same said opposite direction to disconnect and disposeof the needle without inadvertent injury by contact with the needle.Another embodiment has protrusions on the needle and a retractablesheath slidably mounted on the needle and movable between a rearwardretracted position exposing the needle front end and a forwardprotective position engaging the protrusions and covering the front endof the needle. A further modification has a tubular catheter slidablyreceived on the needle for hypodermic penetration therewith which isremovably connected to the sheath whereby when the sheath and needle areremoved from the catheter only the catheter remains in place.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross section of a preferred sheathedhypodermic needle in accordance with the present invention shown withthe sheath in the forward protective position enclosing the front end ofthe needle.

FIG. 2 is a longitudinal cross section of the sheathed hypodermic needleof FIG. 1 shown with the sheath in the rearward retracted positionexposing the front end of the needle.

FIG. 3 is a side elevation of the rear portion of the needle bodyshowing an alternate base configuration.

FIG. 4 is a partial enlarged longitudinal cross section of the rearportion of the sheath member showing the slot configuration with thespring and needle removed.

FIG. 5 is a partial enlarged longitudinal cross section of the rearportion of the sheath member showing the pin members of the needle atthe rear of the slot configuration.

FIG. 6 is an enlarged transverse cross section of the sheathed needletaken along line 6--6 of FIG. 1 showing the pin members of the needleengaged with the sheath in the forward protective position wherebyrelative longitudinal and rotational movement between the needle and thesheath is allowed.

FIG. 7 is an enlarged transverse cross section of the sheathed needleshowing the pin members of the needle engaged with the sheath in theforward protective position whereby relative longitudinal movementbetween the needle and the sheath is prevented while allowing rotationalmovement as a single unit in one direction about their longitudinalaxis.

FIG. 8 is an enlarged transverse cross section of the sheathed needleshowing the pin members of the needle locked within the sheath to securethe sheath in the forward protective position whereby both relativerotational and longitudinal movement between the needle and the sheathis prevented while allowing rotational movement in one direction as asingle unit about their longitudinal axis to facilitate disconnection ofthe needle from the fluid ejection or withdrawal means.

FIG. 9 is a longitudinal cross section of another preferred sheathedhypodermic needle having a manually movable protective sheath shown withthe sheath in the rearward retracted position exposing the front end ofthe needle.

FIG. 10 is a longitudinal cross section of the embodiment of FIG. 9shown with the sheath in the forward protective position enclosing thefront end of the needle.

FIG. 11 is an isometric view of the embodiment of FIG. 9 shown with thesheath in an intermediate position.

FIG. 12 is an isometric view of a "butterfly" modification of theembodiment of FIG. 9 having lateral tabs to facilitate securing theneedle to the patient.

FIG. 13 is a plan view of the "butterfly" modification of FIG. 12showing overlapped lateral tabs.

FIG. 14 is a longitudinal cross section of a preferred sheathedhypodermic catheter-needle having a manually movable protective sheathand a removable sheath enclosing the forward end of the needle andcatheter.

FIG. 15 is a longitudinal cross section of the catheter-needleembodiment of FIG. 14 shown with the removable sheath removed and thecatheter and needle inserted into the patient.

FIG. 16 is a longitudinal cross section of the catheter-needleembodiment of FIG. 14 shown with the needle being removed and thecatheter remaining in place.

FIG. 17 is a longitudinal cross section of the catheter-needleembodiment of FIG. 14 showing the catheter in place after the needle hasbeen completely removed.

FIG. 18 is an isometric view of the catheter-needle embodiment of FIG.14 showing the removable sheath removed.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawings by numerals of reference, there is shown inFIGS. 1 and 2, a preferred hypodermic needle with a protective sheath10. The tubular needle body 11 has a reduced diameter forward portion 12with a beveled or pointed front end 13 to facilitate hypodermicinsertion and an enlarged diameter rearward portion 14 having a basemember 15 secured at the back end in communication with the interior ofthe needle. The base member 15 may be provided with internal threads 16for threaded connection to a hypodermic syringe S. Alternatively, asshown in FIG. 3, the base member 15 may have a smooth interior bore 17for receiving the end of an intravenous tubular member. A pair ofopposed pins 18 extend transversely outward from the enlarged diameter14 of the needle body 11 adjacent the reduced diameter forward portion12.

A tubular sheath 19 surrounds the forward portion of the needle 11. Thesheath 19 has a rounded front end wall 20 with a central aperture 21therethrough which is of sufficient size to allow passage of the forwardportion 12 of the needle 11. A cylindrical plug 22 encloses the rear endof the sheath 19. Cylindrical plug 22 (FIGS. 4 and 5) has a central bore23 extending from the rearward end and a larger diameter bore 24extending from the forward end coaxial therewith. Needle body 11 isslidably received through bores 23 and 24 with bore 23 slidably carriedon the rearward portion 14 of needle (FIG. 5).

A compression spring 25 surrounds the forward portion of needle 11 andhas one end engaged on the interior of the front end wall 20 of sheath19 and its opposite end received within bore 24 of plug 22 and engagedon pins 18 to normally urge needle 11 rearward relative to sheath 19whereby the front end 13 of the needle is retracted within the sheath(FIGS. 1 and 5).

As best seen in FIG. 4, the plug 22 has a pair of laterally opposedslots 26 through its side wall which extend longitudinally from itsfront end and each terminate in a partial radial slot 27 forming agenerally T-shaped guide slot on opposite sides of the plug 22. Theslots 26 and 27 are of sufficient size to slidably receive the pins 18when they are aligned with the slots.

One side 28 of each partial radial slot 27 is smoothly connected withthe longitudinal slot 26 and the opposite side 29 of the radial slot 27is provided with a restriction or protuberance, such as a barb 30 nearits juncture with the longitudinal slot 26. The guide slot configurationallows the pins 18 to slide within the slot 26 (FIGS. 1, 5, and 6). Asseen in FIG. 7, upon relative rotation between the sheath 19 and theneedle 11 in one direction the pins 18 enter the side 28 of the slot 27.As seen in FIG. 8, when relative rotation between the members in theopposite direction is attempted, the rotation must be forced to snap thepins 18 past protuberances 30 in the slot side 29.

In this manner, spring 25 normally urge pins I8 to the rearward end ofslot 26, and needle 11 and sheath 19 are rotated to position pins 18within side slot 28, which maintains the end 13 of needle 11 retractedWithin sheath 19. In this position, there is no longitudinal slidingmovement between needle 11 and sheath 19 and base 15 of the needle maybe connected to an intravenous tube or threaded onto the end of ahypodermic syringe. In the event of a threaded connection, the needleand sheath may be rotated as a single unit in one direction (FIG. 7) tomake up the threaded connection.

After the end connection is made, sheath 19 is rotated in the oppositedirection to position pins 18 within longitudinal slots 26. When in thisposition, the sheath and needle will move longitudinally relative to oneanother. The end 20 of sheath 19 is placed on the surface of the skinand needle 11 is moved forward relative to the sheath to penetrate theskin. As the needle is withdrawn, spring 25 forces sheath 19 forward andthe end 13 of the needle is once again retracted within the sheath. Therearward end of the needle is then disconnected from the intravenoustube or the hypodermic syringe.

As seen in FIG. 8, to disconnect a threaded connection, sheath 19 isrotated to unscrew the threads while the needle is connected to thesyringe causing relative rotation between sheath 19 and needle 11. Thiscauses pins 18 to be forced into slot side 29 past protuberances 30.Thus, relative rotation between the members in the opposite directionsnaps pins 18 into the side 29. The protuberances 30 now lock pins 18into the side 29.

This locking position can also be accomplished by grasping the sheathand the rearward end of the needle and twisting them in the oppositedirection to snap pins 18 into slot side 29. Once pins 18 are secured inslot side 29, both relative rotational and longitudinal movement betweenthe members is prevented and the end of the needle is safely retractedwithin the sheath. This allows the used needle to be safely handled anddisposed of without the danger of accidental pricking or reuse.

MANUALLY MOVABLE EMBODIMENT

Referring to the drawings by numerals of reference, there is shown inFIGS. 9, 10, and 11, a hypodermic needle, designated generally bynumeral 31 having a slidable protective sheath member which is manuallymovable to cover the pointed end of the needle. The hollow tubularneedle body 32 has a beveled front end 33 to facilitate hypodermicinsertion and a base member 34 secured at the back end in communicationwith the interior bore of the needle.

A pair of small laterally opposed projections 35 are formed on theexterior of needle body 32 near beveled front end 33. In a preferredembodiment, needle body 32 is slightly flattened forming a slightlyflattened portion 36 and small laterally opposed projections 35 on theexterior of the needle body. The side walls of flattened portion 36 ofthe needle body are spaced sufficiently apart such that fluid flowthrough the interior of the needle body is not obstructed. It should beunderstood that small projections 35 may also be formed on the exteriorof the needle body 111 by other conventional methods rather than byflattening such that the needle body 32 remains round.

The base member 34 may be provided with internal threads 37 for threadedconnection to a hypodermic syringe, or alternatively as previouslydescribed and shown in FIG. 3, may have a smooth interior bore 17 forreceiving the end of an intravenous tubular member when the needle is inuse or a conventional end cap or plug (not shown) when not in use. Theexterior of base member 34 has a reduced diameter front portion 38 and aradial flange 39 near the reduced diameter portion 38. The reduceddiameter portion 38 is rearward and outwardly tapered.

A cylindrical protective sheath member 40 is slidably received on theexterior of needle body 23. The exterior of the protective sheath member40 has a reduced diameter portion 41 at the forward end which tapersrearward and outwardly. The interior of the protective sheath member 40has a small central bore 42 at the forward end and a coaxial larger bore43 at the rearward end.

The small diameter bore 42 is sized to slide axially on the exterior ofneedle body 32 and in its forward position to frictionally engage thesmall laterally opposed projections 35 on the exterior of the needlebody and is of sufficient length to cover beveled front end 33 of needlebody 32. Larger bore 43 at the rearward end of protective sheath member40 is sized and tapered rearward and outwardly to receive and engagetapered reduced diameter front portion 38 of needle base 34.

In the protective position, cylindrical protective sheath member 40 isin the forward position and frictionally engaged on small laterallyopposed projections 35 on exterior of the needle body 32 to coverbeveled front end 33 of the needle. In this position, there is nolongitudinal sliding movement between needle 32 and protective sheath40.

When threadedly connecting needle base 34 onto the end of a hypodermicsyringe, needle 32 and protective sheath 40 may be rotated as a singleunit to make up the threaded connection. After the end connection ismade, the protective sheath 40 may be manually pulled to the rearposition to frictionally engage it on reduced diameter portion 38 ofneedle base 34. When needle base 34 is connected to an intravenous tube,protective sheath 40 is moved to its rear protective position prior tohypodermic insertion into the skin.

After the needle has been used, protective sheath 40 is manually pushedto the forward position to once again frictionally engage it on smalllaterally opposed projections 35 on the exterior of needle body 32 tocover beveled front end 33 of the needle. In this position, the needlecan be safely handled and disposed of without the danger of accidentalpricking or reuse.

FIG. 12 shows a "butterfly" modification of the needle wherein the base34a of the needle body 32a and the base of the protective sheath member40a each have a pair of opposed flexible "wings" or tabs 34b extendinglaterally outward from their exterior diameters. The tabs 34b and 40bprovide a flat surface to facilitate securing the needle and/orprotective sheath member to the patient with tape. Each pair of flexibletabs 34b or 40b may be bent upward and pinched together with thefingertips to facilitate handling. As seen in FIG. 13, one pair of theflexible tabs may also be sized to overlap the other whereby they may bebent and pinched together as a single pair when the protective sheathmember 40a is in the rear position.

CATHETER-NEEDLE EMBODIMENT

Referring to the drawings by numerals of reference, there is shown inFIGS. 14 through 18, an intravenous catheter-needle combinationdesignated generally by numeral 45 having a sliding protective sheathwhich is manually movable to cover the pointed end of the needle and aremovable protective sheath which covers the forward end of the needleand catheter.

As previously described with reference to FIGS. 9-11, hollow tubularneedle body 32 has a beveled front end 33 to facilitate hypodermicinsertion and a base member 34 secured at the back end in communicationwith the interior bore of the needle. A pair of small laterally opposedprojections 35 are formed on the exterior of needle body 32 near beveledfront end 33. In the preferred embodiment, needle body 32 is slightlyflattened forming a slightly flattened portion 36 and small laterallyopposed projections 35 on the exterior of the needle body. The sidewalls of flattened portion 36 of needle body 32 are spaced sufficientlyapart such that fluid flow through the interior of the needle body isnot obstructed.

It should be understood that small projections 35 may also be formed onthe exterior of needle body 32 by other conventional methods rather thanby flattening such that needle body 32 remains round.

Base member 34 of the catheter-needle embodiment has a smooth interiorbore 17 for receiving the end of an intravenous tubular member when theneedle is in use or a conventional end cap or plug (not shown) when notin use. The exterior of the base member 34 has a reduced diameter frontportion 38 and a radial flange 39 near reduced diameter portion 38. Thereduced diameter portion 38 is rearward and outwardly tapered.

A cylindrical protective sheath member 40 is slidably received on theexterior of needle body 32. The exterior of protective sheath member 40has a reduced diameter portion 41 at the forward end which tapersrearward and outwardly. The interior of protective sheath member 4 has asmall central bore 42 at the forward end and a coaxial larger bore 43 atthe rear end. The small diameter bore 42 is sized to slide axially onthe exterior of needle body 32 and in its forward position tofrictionally engage the small laterally opposed projections 35 on theexterior of the needle body and is of sufficient length to cover beveledfront end 33 of the needle.

The larger bore 42 at the rearward end of protective sheath member 40 issized and tapered rearward and outwardly to receive and frictionallyengage the tapered reduced diameter front portion 38 of needle base 34.When assembled and prior to use, protective sheath member 40 is in therearward position engaged on front portion 38 of the base of the needle.

An intravenous tubular catheter 46 is slidably received on the frontportion of the needle. The catheter 46 has a flexible tubular frontportion 47 which is adapted for intravenous insertion and a base member48 secured at the back end in communication with the interior of tubularportion 47. The interior diameter of tubular front portion 47 closelysurrounds needle body 32 but allows axial sliding movement of needleprojections 35 therethrough. An intermediate portion 49 of the cathetersurrounds tubular portion 47 at its juncture with the base 48 and has anannular bead 50 on its exterior surface. The intermediate portion has asmall interior diameter which engages and seals the exterior of tubularportion 47 and a reduced diameter front portion of base member 48 tojoin them together.

The catheter base member 48 has a small interior bore at its forward endwhich is sized to allow axial sliding movement of needle projections 35therethrough and a coaxial larger interior diameter 52 at its rearwardend which is sized to receive the end of an intravenous tubular memberwhen the needle is removed or a conventional end cap or plug (not shown)when not in use. The tapered front end 41 of protective sheath member 40is sized to be frictionally received and engaged in bore 52 of basemember 48 of catheter 46. When assembled and prior to use, protectivesheath member 40 is in the rearward position engaged on front portion 38of needle base 34, and base member 48 of catheter 46 is in the rearwardposition engaged on front portion 41 of protective sheath member 40. Thelength of the catheter tubular portion 47 is slightly smaller than thelength of needle 32 so that beveled front end 33 of the needle isexposed to facilitate intravenous insertion of both needle 32 andtubular portion 47 of catheter 46.

A removable tubular protective sheath 53 surrounds the forward portionof needle 32 and tubular portion 47 of catheter 46. The removabletubular sheath 53 has an enclosed front end 54 and its interior diameteris sized to receive and frictionally engage exterior bead 50 onintermediate portion 49 of catheter 46. The open end of removable sheath53 may be provided with a radial flange 55 to facilitate installationand removal.

Thus in the completely assembled condition, the protective sheath member40 is in the rearward position engaged on the front portion 38 of base34 of needle 32, base member 48 of catheter 46 is in the rearwardposition engaged on front portion 41 of protective sheath member 40, andremovable sheath 53 is frictionally engaged on bead 50 of intermediateportion 49 of catheter 46 and surrounds the forward portion of needle 32and tubular portion 47 of catheter 46.

To use the catheter-needle combination, removable sheath 53 is removedfrom catheter 46. The beveled end 33 of needle 32 having tubular portion47 of catheter 46 surrounding its length is inserted into the vein.While catheter 46 and protective sheath 40 are held stationary, base 43of needle 32 is drawn rearward with protective sheath member 40 stillengaged with base 48 of catheter 46.

As needle 32 is completely withdrawn from catheter 46, projections 35 onthe forward portion of needle 32 slide through tubular portion 47 andbase 48 of catheter 46 and become frictionally engaged in interior bore42 at the forward end of protective sheath member 40 and pull it out ofcatheter base member 48 as the needle is removed (FIG. 16). Thus, asneedle 32 is removed, protective sheath member 40 is caused to assumeits forward protective position covering beveled end 33 of needle 32 andit can be safely handled and disposed of without the danger ofaccidental pricking or reuse.

As seen in FIG. 17, after needle 32 is removed, only flexible tubularportion 47 of catheter 46 remains beneath the skin, the properconnections are made at base 48 of the catheter, and it may be securedin place by tape or other conventional means. By completely withdrawingthe needle, the catheter has unobstructed fluid flow through itsinterior. After catheter 46 is removed from the patient, removablesheath 53 may be reinstalled over flexible tubular portion 47 and theused catheter properly disposed of.

FIG. 18 shows a "butterfly" modification of the catheter-needleembodiment wherein base 48 of catheter 46 and/or the retractable sheath40 each may have a pair of opposed flexible "wings" or tabs 56 extendinglaterally outward from their exterior diameters. The tabs 56 provide aflat surface to facilitate securing the catheter and/or protectivesheath member to the patient with tape. Each pair of flexible tabs 56may be bent upward and pinched together with the fingertips tofacilitate handling. As previously shown and described with reference toFIG. 13, one pair of the flexible tabs may also be sized to overlap theother whereby they may be bent and pinched together as a single pair.

While this invention has been described fully and completely withspecial emphasis upon a preferred embodiment, it should be understoodthat within the scope of the appended claims the invention may bepracticed otherwise than as specifically described herein.

I claim:
 1. A sheathed hypodermic needle comprisinga tubular fluid handling needle having a front end adapted for hypodermic penetration and a rear end adapted for connection to fluid ejection or withdrawal means, protrusions on the exterior forward portion of said needle formed by flattening a portion of said needle near its front end to cause a portion of the needle exterior diameter to protrude outward sufficient to frictionally engage the interior of said sheath while allowing unobstructed fluid flow through the needle interior, a retractable sheath slidably mounted on said needle and movable relative thereto between a rearward retracted position exposing the front end of said needle and a forward protective position enclosing the front end of said needle to prevent inadvertent injury by contact with said needle and to facilitate disposal of said needle, the interior of said sheath adapted to frictionally engage said protrusions in said forward protective position and cover the front end of said needle.
 2. A sheathed hypodermic needle according to claim 1 in whichsaid retractable sheath comprises a tubular member coaxially surrounding a portion of said needle and having a back end adapted to be slidably received and frictionally engaged on said needle rear base portion, and said sheath slidable axially rearward relative to said needle upon application of axial force to allow the front end of said needle to protrude beyond the front end of said sheath for hypodermic penetration and to engage said sheath on said needle rear base portion.
 3. A sheathed hypodermic needle according to claim 2 in whichsaid sheath back end having a central bore which is capable of being slidably received and frictionally engaged on said needle rear base portion.
 4. A sheathed hypodermic needle according to claim 1 in whichsaid sheath is frictionally engaged on said needle protrusions in the forward protective position whereby relative longitudinal movement between said needle and said sheath is prevented while allowing rotational movement as a single unit about their longitudinal axis to facilitate connection of said needle base to fluid ejection or withdrawal means.
 5. A sheathed hypodermic needle according to claim 1 in whichsaid sheath has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation to facilitate securing said needle to the patient.
 6. A sheathed hypodermic needle according to claim 1 in whichsaid needle base has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation to facilitate securing said needle to the patient.
 7. A sheathed hypodermic needle comprisinga tubular fluid handling needle having a front end adapted for hypodermic penetration and a rear end adapted for connection to fluid ejection or withdrawal means, protrusions on the exterior forward portion of said needle, a retractable sheath slidably mounted on said needle and movable relative thereto between a rearward retracted position exposing the front end of said needle and a forward protective position enclosing the front end of said needle to prevent inadvertent injury by contact with said needle and to facilitate disposal of said needle, the interior of said sheath adapted to frictionally engage said protrusions in said forward protective position and cover the front end of said needle, said needle base has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation, and said sheath has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation to facilitate securing said needle to the patient.
 8. A sheathed hypodermic needle according to claim 1 includinga tubular fluid handling catheter slidably received on said needle and having a flexible tubular front portion closely surrounding the front portion of said needle and said protrusions and leaving said needle front end exposed for hypodermic penetration therewith and a rear base portion adapted for removable connection to said retractable sheath for axial movement therewith or for connection to fluid ejection or withdrawal means, whereby when said retractable sheath is in its rear position and said catheter is connected to said retractable sheath, the front portion of said needle and said catheter may be hypodermically inserted into a subject as a single unit, and after insertion, said needle may be withdrawn until said retractable sheath is in its forward protective position covering the front end of said needle and said retractable sheath and said needle may be disconnected and removed from said catheter base to leave only said catheter hypodermically installed into the subject, and after said retractable sheath and said needle are removed, said catheter base may be connected to fluid ejection or withdrawal means.
 9. A sheathed hypodermic needle according to claim 8 in whichsaid retractable sheath comprises a tubular member coaxially surrounding a portion of said needle and having a front end adapted to be slidably received and frictionally engaged on said catheter rear base portion, and said catheter rear base portion having a central bore which is capable of being slidably received and frictionally engaged on said retractable sheath front end.
 10. A sheathed hypodermic needle according to claim 8 includinga removable tubular protective sheath having an enclosed front end and an open back end adapted for removable connection to said catheter base to surround and enclose the forward portion of said catheter and said needle front end when said needle and catheter is not in use.
 11. A sheathed hypodermic needle according to claim 10 in whichsaid catheter has an intermediate portion between its base and its tubular portion, and the interior of said tubular removable sheath back end is adapted to frictionally engage said intermediate portion in its connected condition.
 12. A sheathed hypodermic needle according to claim 8 in whichsaid catheter base has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation to facilitate securing said catheter to the subject.
 13. A sheathed hypodermic needle according to claim 8 in whichsaid sheath has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation to facilitate securing said needle to the subject.
 14. A sheathed hypodermic needle according to claim 8 in whichsaid catheter base has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation, and said sheath has a pair of flat flexible tabs extending outwardly from its exterior in laterally opposed relation to facilitate securing said catheter and needle to the subject. 